Your user account has not been hacked.
It has been a long-standing policy here to use real names on this site, but in the past, it was not heavily enforced.
Around the first of the year we switched to new software, which insists on a "FirstName/LastName format.
Those whose names did not comply were automatically given either Hatfield, or McCoy as a last name.
Please see the following thread for more details:
https://permies.com/forums/posts/list/1621#10035
There will probably be some date in the future when all non-compliant accounts get locked out. We are strongly suggesting that those who need to change their names do so quickly.
To change your name to a compliant one, go to "My Profile" and do a name change request.
For those who feel that they are "known all over the web" as "[UserName]", you can add a line to your signature saying something like:
"Formerly known as [UserName]", or "aka [UserName]"
As a side note: After you have changed your user name, logon is still done using your original username. If you need help with passwords, etc, using your email address will get you recognized by the system.